1. Field of the Invention
The present invention relates to subsurface well drilling equipment and, more particularly, to apparatus for connecting and disconnecting components of a bottom hole assembly to a tubing, but preferably coiled tubing, and for connecting and disconnecting components to other components of the bottom hole assembly.
2. Description of the Related Art
A Bottom Hole Assembly (commonly referred to in the industry as a BHA) for drilling wells with a coiled tubing comprises various constituent parts which may include: a drill bit, a bent sub for changing the vertical angle of penetration, a motor for rotating the bit, a circulating sub for flowing drilling mud to prevent sticking of the BHA in the well, an orienting tool for changing the direction of penetration, a thruster for providing weight on the bit, and a sub which provides a means for selectively attaching and releasing the BHA from the coiled tubing. The present invention is directed to a device which is a significant improvement over the prior art for selectively attaching and releasing the BHA from the coiled tubing.
While drilling wells, it is possible for the BHA to become lodged downhole due to differential pressure that may exist in the well and/or a cave-in of the hole, or excessive friction due to well trajectory. Coiled tubing has a relatively smaller wall thickness than conventional drill pipe, and therefore has a reduced tensile strength, and therefore a reduced capacity to pull a lodged BHA from a well. This is especially true if a portion of the well has been drilled horizontally. If the tensile strength of the coiled tubing is exceeded while attempting to pull the BHA from the well, tensile failure can occur, resulting in an unpredictable parting of the tubing. The presence of an unpredictable length and configuration of coiled tubing left in the well with the lodged BHA makes retrieval difficult, if not impossible, and can result in the loss of the expensive BHA and the possible abandonment of the well. Prior art references are as follows, all of which are U.S. Pat. Nos. 5,323,853; 4,476,945; 4,913,229; 5,265,675.
There is a need for a device to allow coiled tubing to be easily pulled from or attached to the connector on a first end, and on a second end, have a connector that may quickly and easily be removed from and attached to the BHA.